Many pulp mills employ what is known as the Kraft chemical recovery process. In this process, black liquor is burned in a recovery boiler and produces ash which includes sodium. Typically, the sodium is recovered from the ash in the form of sodium sulfate and sodium carbonate. Some ashes include a relatively high content of carbonate. In certain types of recovery processes, especially those employing a two-stage process, the presence of the high carbonate content in the ash impacts the overall efficiency of sodium recovery.